Device to device-based communication method and terminal

ABSTRACT

Provided in the embodiment of the present invention are a D2D-based communication method and a terminal. The method comprises: a first terminal receives a discovery signal of a second terminal, the discovery signal comprising indication information for indicating the capability and/or the status of the second terminal; and the first terminal performs D2D communication with the second terminal on the basis of the instruction information. The embodiment of the present invention implements the D2D communication on the basis of the capability and/or status of the terminal, improving the flexibility of the D2D communication mode.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/779,035, filed on May 24, 2018, which is a US national phaseapplication based upon International Application No. PCT/CN2016/076806,filed on Mar. 18, 2016. The entire contents of the above applicationsare incorporated herein by reference in their entireties.

TECHNICAL FIELD

Embodiments of the disclosure relate to the field of wirelesscommunication, and more particularly to a Device to Device (D2D)-basedcommunication method and a terminal.

BACKGROUND

Conventional mobile communication usually adopts acellular-network-based communication manner. Specifically, in a cellularnetwork, when a source terminal is to transmit data to a targetterminal, the source terminal is to establish a connection with a basestation at first, and then the data of the source terminal is sent tothe target terminal through the base station.

Long Term Evolution (LTE) Release 12 (R12) introduces a D2Dcommunication technology, also called as a D2D technology. In the D2Dcommunication technology, a terminal may directly communicate withanother terminal by virtue of a resource allocated by a base station.

The whole D2D process may substantially be divided into a D2D discoveryprocess and a D2D communication process, wherein, in the D2D discoveryprocess, a D2D terminal may detect a discovery signal broadcast byanother D2D terminal, thereby detecting existence of the other D2Dterminal in a short-distance range and recognizing identity informationof the other D2D terminal. In the D2D communication process, the D2Dterminals may perform data exchange in multiple forms of voicecommunication, multimedia information sharing or the like at a shortdistance.

LTE R13 introduces a D2D cooperative relay communication technology. Byvirtue of the D2D cooperative relay communication technology, when aterminal is located in an environment without network coverage ornetwork coverage of the terminal is poorer, the terminal may access abase station (or access a network) by taking another terminal located inthe network coverage as an access board. The terminal taken as theaccess board may be called as a relay terminal or a relay node.

In a future wireless communication system, besides conventionalterminals, there may appear more and more terminals of other types, forexample, a smart band, a wireless television, smart glasses, a robot anda watch, and the terminals of these special types are lower in cost, maynot have a function of directly accessing a base station and usuallyrequire relay terminals for accessing the base station. The terminals ofthese special types may support different bandwidths and transmit power.In addition, in a D2D cooperative relay communication technology,different relay terminals may be in different states. For example, arelay terminal of which electricity amount or load reaches a certainthreshold value may not provide access service for a new terminal.

However, in a conventional art, terminals perform D2D discovery and D2Dcommunication according to a unified manner and may not make regulationsaccording to practical conditions of the terminals, so that such acommunication manner is not so flexible.

BRIEF DESCRIPTION OF DRAWINGS

In order to describe the technical solutions of the embodiments of thedisclosure more clearly, the drawings required to be used in theembodiments of the disclosure will be simply introduced below.Obviously, the drawings described below are only some embodiments of thedisclosure. Other drawings may further be obtained by those of ordinaryskilled in the art according to these drawings without creative work.

FIG. 1 is a schematic diagram of a protocol stack format of a discoverysignal.

FIG. 2 is a schematic flowchart of a D2D-based communication methodaccording to an embodiment of the disclosure.

FIG. 3 is a schematic flowchart of a D2D-based communication methodaccording to an embodiment of the disclosure.

FIG. 4 is a schematic structure diagram of a terminal according to anembodiment of the disclosure.

FIG. 5 is a schematic structure diagram of a terminal according to anembodiment of the disclosure.

DETAILED DESCRIPTION

It should be understood that the technical solutions of the disclosuremay be applied to various communication systems, for example, a GlobalSystem of Mobile Communication (GSM), a Code Division Multiple Access(CDMA) system, a Wideband Code Division Multiple Access (WCDMA) system,a General Packet Radio Service (GPRS), an LTE system, an Advanced LTE(LTE-A) system, a Universal Mobile Telecommunication System (UMTS) and5th-Generation.

It should also be understood that, in the embodiments of the disclosure,a terminal may be a mobile terminal, and includes, but not limited to,User Equipment (UE), a Mobile Station (MS), a mobile telephone, ahandset, portable equipment and the like. The UE may communicate withone or more core networks through a Radio Access Network (RAN). Forexample, the UE may be a mobile telephone (or called as a “cellular”telephone) and a computer with a wireless communication function, andthe UE may also be a portable, pocket, handheld, computer-built-in orvehicle-mounted mobile device. In addition, the terminal of theembodiments of the disclosure may further be a terminal of another type,besides a conventional handheld terminal, including a smart band, awireless television, smart glasses, a robot, a watch and the like.

In the embodiments of the disclosure, a base station may be a BaseTransceiver Station (BTS) in the GSM or CDMA, may also be a NodeB inWCDMA, may further be an Evolved Node B (eNB or e-NodeB) in LTE, and mayfurther be an access point with an access function with a 5Gcommunication network, which will not be limited in the embodiments ofthe disclosure.

From the above, it can be seen that, in a future wireless communicationsystem, besides conventional terminals, there may appear more and moreterminals of other types, and terminals of different types may havedifferent capabilities or states. Therefore, before performing D2Dcommunication, a terminal may make another terminal to know about itsown capability or state in a certain manner, for example, making theother terminal to know about whether the terminal is a low-cost andsmall-bandwidth terminal, maximum transmit power, electricity amount andload of the terminal and whether the terminal may receive data, for theother terminal to perform D2D communication with the terminal byadopting a proper communication mode.

Before D2D communication, a terminal expecting to initiate D2Dcommunication may send a discovery signal to terminals around it. Insome embodiments, indication information may be contained in thediscovery signal of the terminal, and the indication information may beconfigured to indicate a capability or state of the terminal.

A capability of a terminal may, for example, include at least one of: abandwidth supported by the terminal; transmit power of the terminal;whether the terminal may serve to enable another terminal to access abase station as a relay terminal; and a type of a service for which theterminal allows access of the other terminal as the relay terminaland/or a priority (or probability) of the service for which access ofthe other terminal is allowed. A state of a terminal may, for example,include at least one of: a load of the terminal and electricity amountof the terminal.

The application provides a D2D-based communication method and aterminal, so as to improve flexibility of a D2D communication manner.

Embodiments of the disclosure provide a D2D-based communication method.The method may include the following actions. A first terminal receivesa discovery signal of a second terminal. The discovery signal includesindication information and the indication information is configured toindicate at least one of a capability of the second terminal or a stateof the second terminal. The first terminal performs D2D communicationwith the second terminal according to the indication information.

According to an embodiment, the second terminal may be a relay terminal.The second terminal may access a base station through the firstterminal. The indication information may be configured to indicate thecapability of the second terminal. The action of performing, by thefirst terminal, D2D communication with the second terminal according tothe indication information may include the following actions. The firstterminal determines a communication manner matched with the capability,indicated by the indication information, of the second terminalaccording to the indication information. During the second terminalaccessing the base station through the first terminal, the firstterminal performs D2D communication with the second terminal in thecommunication manner.

According to an embodiment, the indication information may be configuredto indicate a capability level of the second terminal. The capabilitylevel of the second terminal may be one of multiple preset capabilitylevels. The action of determining, by the first terminal, thecommunication manner matched with the capability of the second terminalaccording to the indication information may include the followingactions. The first terminal determines the capability level of thesecond terminal according to the indication information. The firstterminal determines the capability of the second terminal through apreset correspondence between capability levels and capabilities of aterminal according to the capability level of the second terminal. Thefirst terminal determines the communication manner matched with thecapability of the second terminal.

According to an embodiment, the capability of the second terminal mayinclude at least one of a bandwidth supported by the second terminal andtransmit power of the second terminal.

According to an embodiment, the first terminal may access the basestation through the second terminal. The indication information may beconfigured to indicate the state of the second terminal. The action ofperforming, by the first terminal, D2D communication with the secondterminal according to the indication information may include thefollowing actions. The first terminal determines the state of the secondterminal according to the indication information. The first terminaldetermines whether the base station may be accessed through the secondterminal according to the state of the second terminal. When the firstterminal determines that the base station may be accessed through thesecond terminal, the first terminal performs D2D communication with thesecond terminal to access the base station.

According to an embodiment, the indication information may be configuredto indicate a state level of the second terminal. The state level of thesecond terminal may be one of multiple preset state levels. The actionof determining, by the first terminal, the state of the second terminalaccording to the indication information may include the followingactions. The first terminal determines the state level of the secondterminal according to the indication information. The first terminaldetermines the state of the second terminal through a presetcorrespondence between state levels and states of a terminal accordingto the state level of the second terminal.

According to an embodiment, the indication information may be configuredto indicate whether the second terminal allows another terminal toaccess the base station through the second terminal.

According to an embodiment, the action of determining, by the firstterminal, the state of the second terminal according to the indicationinformation may include the following actions. The first terminaldetermines a service type set or terminal set for which the secondterminal allows one or more terminals other than the second terminal toaccess the base station through the second terminal according to theindication information. The action of determining, by the firstterminal, whether the base station may be accessed through the secondterminal according to the state of the second terminal may include thefollowing actions. The second terminal sends the indication informationin the discovery signal to indicate the service type set or terminal setallowed for access. The first terminal determines whether a service typeof a present service of the first terminal belongs to the service typeset or whether the first terminal belongs to the terminal set. When theservice type of the present service belongs to the service type set orthe first terminal belongs to the terminal set, the first terminaldetermines that the base station may be accessed through the secondterminal. When the service type of the present service does not belongto the service type set or the first terminal does not belong to theterminal set, the first terminal determines that the base station maynot be accessed through the second terminal.

According to an embodiment, the state of the second terminal may referto the service type set for which the second terminal may provideaccess. Or, the state of the second terminal may refer to the terminalset for which the second terminal may provide access.

According to an embodiment, the action of determining, by the firstterminal, the state of the second terminal according to the indicationinformation may include the following actions. The first terminaldetermines an access probability of the present service of the firstterminal or a terminal category of the first terminal. The action ofdetermining, by the first terminal, whether the base station may beaccessed through the second terminal according to the state of thesecond terminal may include the following actions. The first terminalgenerates a random number and calculates a probability of the randomnumber. When the probability of the random number meets the accessprobability, the first terminal determines that the base station may beaccessed through the second terminal. When the probability of the randomnumber does not meet the access probability, the first terminaldetermines that the base station may not be accessed through the secondterminal.

According to an embodiment, the state of the second terminal may includeelectricity amount or load of the second terminal. The action ofdetermining, by the first terminal, the state of the second terminalaccording to the indication information may include the followingactions. The first terminal determines the electricity amount or load ofthe second terminal according to the indication information. The actionof determining, by the first terminal, whether the base station may beaccessed through the second terminal according to the state of thesecond terminal may include the following actions. When the electricityamount is larger than a preset electricity amount threshold value or theload of the second terminal is larger than a preset load thresholdvalue, the first terminal determines that the base station may beaccessed through the second terminal. When the electricity amount of thesecond terminal is smaller than the electricity amount threshold valueor the load of the second terminal is smaller than the load thresholdvalue, the first terminal determines that the base station may not beaccessed through the second terminal.

According to an embodiment, the state of the second terminal may includeat least one of the electricity amount of the second terminal and theload of the second terminal.

According to an embodiment, the indication information may be includedin Downlink Control Information (DCI) of a Physical (PHY) layer of thediscovery layer.

According to an embodiment, the indication information may be includedin a Media Access Control (MAC) Control Element (CE) of the discoverysignal.

According to an embodiment, the indication information may be includedin a Proximity-based Service (ProSe) protocol layer of the discoverysignal.

According to the application, D2D communication is performed on thebasis of at least one of a capability or state of a terminal, so thatflexibility of a D2D communication manner is improved.

FIG. 1 is a schematic diagram of a protocol stack format of a discoverysignal. A protocol stack of the discovery signal may include a ProSeprotocol layer (or called as an upper layer), a MAC layer and a PHYlayer. ProSe may represent Proximity Service, i.e., proximity service,the ProSe protocol layer may include a ProSe identifier of a terminal,and terminals may be mutually recognized through ProSe identifiers andperform D2D communication.

In some embodiments, indication information may be located in the PHYlayer of the indication information, and for example, may be included inDCI of the PHY layer. In an example, the terminal may indicate acapability or state of the terminal through an information field in aDCI format of the PHY layer of the discovery signal.

In some embodiments, the indication information may be located in theMAC layer of the discovery signal, and for example, may be included in aCE of the MAC layer. In an example, the terminal may indicate thecapability or state of the terminal through a bit or index in the MAC CEof the discovery signal.

In some embodiments, the indication information may be located in theProSe protocol layer of the discovery signal. In an example, theterminal may indicate the capability or state of the terminal through aninformation field in the ProSe protocol layer of the discovery signal.

According to the embodiments of the disclosure, an indication manner forthe indication information is not specifically limited, a directindication manner may be adopted, and an indirect indirection manner mayalso be adopted. In some embodiments, the capability or state of theterminal may be divided into a plurality of levels in advance, differentcapability levels may correspond to different capabilities of theterminal, and different state levels may correspond to different statesof the terminal. The indication information specifically includescapability level information and/or state level information. Acapability level or state level-based indication manner may reduce anoverhead in the indication information.

For example, the capability of the terminal may include a bandwidthsupported by the terminal and a maximum bandwidth supported by theterminal. Bandwidth levels of the terminal may be divided in advance,and for example, the bandwidth levels of the terminal may be dividedinto multiple levels of 200 kHz, 1.4 MHz, 5 MHz and the like.

For another example, the capability of the terminal may support transmitpower (for example, maximum transmit power and average transmit power)supported by the terminal. transmit power levels of the terminal may bedivided in advance, and for example, the transmit power levels of theterminal may be divided into levels of 20 dBm, 23 dBm and the like.

For another example, the state of the terminal may include electricityamount of the terminal. Electricity amount levels of the terminal may bedivided in advance, and for example, the electricity amount levels ofthe terminal may be divided into levels of 20%, 50%, 80% and the like.Of course, the state of the terminal may also be another state of a loadof the terminal and the like, and a specific division principle issimilar and will not be elaborated herein.

The embodiments of the disclosure will be described below with a D2Dcooperative relay communication technology as an example in detail.

FIG. 2 is a schematic flowchart of a D2D-based communication methodaccording to an embodiment of the disclosure. In FIG. 2, a firstterminal is a relay terminal, and a second terminal expects to access abase station through the first terminal. It should be understood thatcommunication actions or operations shown in FIG. 2 are only exemplary,and other operations or transformations of various operations in FIG. 2may also be executed in the embodiment of the disclosure. In addition,each action in FIG. 2 may be executed according to a sequence differentfrom that presented in FIG. 2 and there is a probability that not allthe operations in FIG. 2 are required to be executed.

In 210, the second terminal sends a discovery signal.

In some embodiments, when the second terminal expects to initiate D2Dcommunication or the second terminal expects to access the base stationthrough another terminal, the discovery signal may be broadcast. In anexample, the second terminal may be a terminal without network coverageor a low-cost or small-bandwidth terminal incapable of directlyaccessing the base station.

In addition, the discovery signal of the second terminal may containindication information, and the indication information may be configuredto indicate a capability of the second terminal. The capability of theterminal and a containing manner for the indication information in thediscovery signal are described above in detail and will not beelaborated herein to avoid repetitions.

In 220, the first terminal determines a communication manner matchedwith a capability of the second terminal.

For example, the second terminal supports a bandwidth of 200 kHz andtransmit power of 20 dBm. The first terminal may select a correspondingbandwidth resource and transmit power to communicate with the secondterminal.

In 230, the first terminal enables the second terminal to access thebase station as a relay terminal.

during the second terminal accessing the base station through the firstterminal, the first terminal performs D2D communication with the secondterminal in the communication manner determined in Action 220.

In the embodiment of the disclosure, the first terminal may determine aproper communication manner on the basis of the capability of the secondterminal and enable the second terminal to access the base stationaccording to the communication manner, so that flexibility of D2Dcooperative relay communication is improved.

FIG. 3 is a schematic flowchart of a D2D-based communication methodaccording to an embodiment of the disclosure. In FIG. 3, a secondterminal is a relay terminal, and a first terminal expects to access abase station through the second terminal. It should be understood thatcommunication actions or operations shown in FIG. 3 are only exemplary,and other operations or transformations of various operations in FIG. 3may also be executed in the embodiment of the disclosure. In addition,each action in FIG. 3 may be executed according to a sequence differentfrom that presented in FIG. 3 and there is a probability that not allthe operations in FIG. 3 are required to be executed.

In 310, the second terminal sends a discovery signal.

The discovery signal of the second terminal may contain indicationinformation, and the indication information may be configured toindicate a state of the second terminal. For example, presentelectricity amount and load of the second terminal may be contained.

In 320, the first terminal determines whether the base station may beaccessed through the second terminal.

In some embodiments, the indication information may be the electricityamount or load of the second terminal, and at this moment, the secondterminal may select to perform access and data transmission through thesecond terminal according to a preconfigured threshold value. Forexample, for the electricity amount of the second terminal, thethreshold value may be set to be 30% of the electricity amount of thesecond terminal, and when the indication information indicates that theelectricity amount of the second terminal is 20%, the first terminaldoes not access the base station through the second terminal; and whenthe indication information indicates that the electricity amount of thesecond terminal is 40%, the first terminal accesses the base stationthrough the second terminal.

In some embodiments, the indication information may indicate whether thesecond terminal allows another terminal to access the base stationthrough the second terminal; and/or a type of a service for which thesecond terminal allows the other terminal to access the base stationthrough the second terminal and/or an access probability (or priority)of the service. In an example, it may be indicated in the indicationinformation (the indication information may perform indication through,for example, a certain information field of the discovery signal, namelythrough an information bit in the information field) that the secondterminal may provide access for a service 1 and a service 2 and may notprovide access for a service 3. When a present service (service expectedto access the base station) of the first terminal is the service 1, thefirst terminal accesses the base station through the second terminal,and when the present service of the first terminal is the service 3, thefirst terminal does not access the base station through the secondterminal. In another example, it may be indicated in the indicationinformation (the indication information may perform indication through,for example, a certain information field of the discovery signal, namelythrough an information bit in the information field) that an accessprobability of the service 1 is 80% and an access probability of theservice 2 is 30%. When the present service (expected to access the basestation) of the first terminal is the service 1, the indicationinformation indicates that the access probability of the service 1 is80%, and then the first terminal may generate a random number between 0and 1, and when a probability of the random number is lower than 80%(namely falling between 0 and 0.8), the first terminal accesses the basestation through the second terminal, otherwise the first terminal doesnot access the base station through the second terminal.

In 330, when determining that the second terminal may provide accessservice, the first terminal accesses the base station through the secondterminal.

The D2D-based communication method according to the embodiments of thedisclosure is described above in combination with FIG. 1 to FIG. 3 indetail, and a terminal according to the embodiments of the disclosurewill be described below in combination with FIG. 4 to FIG. 5 in detail.It should be understood that the terminal of FIG. 4 or FIG. 5 mayexecute each action executed by the terminal above, and repeateddescriptions are properly eliminated for simplicity.

FIG. 4 is a schematic structure diagram of a terminal according to anembodiment of the disclosure. The terminal 400 of FIG. 4 includes:

a receiving unit 410, configured to receive a discovery signal of asecond terminal, the discovery signal including indication informationand the indication information being configured to indicate a capabilityof the second terminal and/or a state of the second terminal; and

a communication unit 420, configured to perform D2D communication withthe second terminal according to the indication information.

According to the embodiment of the disclosure, D2D communication isperformed on the basis of a capability and/or state of a terminal, sothat flexibility of a D2D communication manner is improved.

In at least one embodiment, the second terminal accesses a base stationthrough a first terminal, the indication information is configured toindicate the capability of the second terminal, and the communicationunit 420 is specifically configured to determine a communication mannermatched with the capability of the second terminal according to theindication information and, during the second terminal accessing thebase station through the first terminal, perform D2D communication withthe second terminal in the communication manner.

In at least one embodiment, the indication information is specificallyconfigured to indicate a capability level of the second terminal, thecapability level of the second terminal is one of multiple presetcapability levels, and the communication unit 420 is specificallyconfigured to determine the capability level of the second terminalaccording to the indication information, determine the capability of thesecond terminal through a preset correspondence between capabilitylevels and capabilities of a terminal according to the capability levelof the second terminal and determine the communication manner matchedwith the capability of the second terminal.

In at least one embodiment, the capability of the second terminalincludes at least one of a bandwidth supported by the second terminaland transmit power of the second terminal.

In at least one embodiment, the first terminal accesses the base stationthrough the second terminal, the indication information is configured toindicate the state of the second terminal, and the communication unit420 is specifically configured to determine the state of the secondterminal according to the indication information, determine whether thebase station may be accessed through the second terminal according tothe state of the second terminal and, responsive to a determinationabout that the base station may be accessed through the second terminal,perform, by the first terminal, D2D communication with the secondterminal to access the base station.

In at least one embodiment, the indication information is specificallyconfigured to indicate a state level of the second terminal, the statelevel of the second terminal is one of multiple preset state levels, andthe communication unit 420 is specifically configured to determine thestate level of the second terminal according to the indicationinformation and determine the state of the second terminal through apreset correspondence between state levels and states of a terminalaccording to the state level of the second terminal.

In at least one embodiment, the indication information is specificallyconfigured to indicate whether the second terminal allows anotherterminal to access the base station through the second terminal.

In at least one embodiment, the communication unit 420 is specificallyconfigured to: determine a service type set or terminal set for whichthe second terminal allows the other terminal to access the base stationthrough the second terminal according to the indication information;determine whether a service type of a present service of the firstterminal belongs to the service type set or whether the first terminalbelongs to the terminal set; when the service type of the presentservice belongs to the service type set or the first terminal belongs tothe terminal set, determine that the base station may be accessedthrough the second terminal; and when the service type of the presentservice does not belong to the service type set or the first terminaldoes not belong to the terminal set, determine that the base station maynot be accessed through the second terminal.

In at least one embodiment, the communication unit 420 is specificallyconfigured to: determine an access probability of the present service ofthe first terminal or a terminal category of the first terminal;generate a random number and calculate a probability of the randomnumber; when the probability of the random number meets the accessprobability, determine that the base station may be accessed through thesecond terminal; and when the probability of the random number does notmeet the access probability, determine that the base station may not beaccessed through the second terminal.

In at least one embodiment, the state of the second terminal includeselectricity amount of load of the second terminal, and the communicationunit 420 is specifically configured to: determine the electricity amountor load of the second terminal according to the indication information;when the electricity amount is larger than a preset electricity amountthreshold value or the load of the second terminal is larger than apreset load threshold value, determine that the base station may beaccessed through the second terminal; and when the electricity amount ofthe second terminal is smaller than the electricity amount thresholdvalue or the load of the second terminal is smaller than the loadthreshold value, determine that the base station may not be accessedthrough the second terminal.

In at least one embodiment, the indication information is included inDCI of a PHY layer of the discovery layer.

In at least one embodiment, the indication information is included in aMAC CE of the discovery signal.

In at least one embodiment, the indication information is included in aProSe protocol layer of the discovery signal.

FIG. 5 is a schematic structure diagram of a terminal according to anembodiment of the disclosure. The terminal 500 of FIG. 5 includes:

a transceiver 510, configured to receive a discovery signal of a secondterminal, the discovery signal including indication information and theindication information being configured to indicate a capability of thesecond terminal and/or a state of the second terminal; and

a processor 520, configured to perform D2D communication with the secondterminal through the transceiver 510 according to the indicationinformation.

According to the embodiment of the disclosure, D2D communication isperformed on the basis of a capability and/or state of a terminal, sothat flexibility of a D2D communication manner is improved.

In at least one embodiment, the second terminal accesses a base stationthrough a first terminal, the indication information is configured toindicate the capability of the second terminal, and the processor 520 isspecifically configured to determine a communication manner matched withthe capability of the second terminal according to the indicationinformation and during the second terminal accessing the base stationthrough the first terminal, perform D2D communication with the secondterminal in the communication manner.

In at least one embodiment, the indication information is specificallyconfigured to indicate a capability level of the second terminal, thecapability level of the second terminal is one of multiple presetcapability levels, and the processor 520 is specifically configured todetermine the capability level of the second terminal according to theindication information, determine the capability of the second terminalthrough a preset correspondence between capability levels andcapabilities of a terminal according to the capability level of thesecond terminal and determine the communication manner matched with thecapability of the second terminal.

In at least one embodiment, the capability of the second terminalincludes at least one of a bandwidth supported by the second terminaland transmit power of the second terminal.

In at least one embodiment, the first terminal accesses the base stationthrough the second terminal, the indication information is configured toindicate the state of the second terminal, and the processor 520 isspecifically configured to determine the state of the second terminalaccording to the indication information, determine whether the basestation may be accessed through the second terminal according to thestate of the second terminal and, responsive to a determination aboutthat the base station may be accessed through the second terminal,perform, by the first terminal, D2D communication with the secondterminal to access the base station.

In at least one embodiment, the indication information is specificallyconfigured to indicate a state level of the second terminal, the statelevel of the second terminal is one of multiple preset state levels, andthe processor 520 is specifically configured to determine the statelevel of the second terminal according to the indication information anddetermine the state of the second terminal through a presetcorrespondence between state levels and states of a terminal accordingto the state level of the second terminal.

In at least one embodiment, the indication information is specificallyconfigured to indicate whether the second terminal allows anotherterminal to access the base station through the second terminal.

In at least one embodiment, the processor 520 is specifically configuredto: determine a service type set or terminal set for which the secondterminal allows the other terminal to access the base station throughthe second terminal according to the indication information; determinewhether a service type of a present service of the first terminalbelongs to the service type set or whether the first terminal belongs tothe terminal set; when the service type of the present service belongsto the service type set or the first terminal belongs to the terminalset, determine that the base station may be accessed through the secondterminal; and when the service type of the present service does notbelong to the service type set or the first terminal does not belong tothe terminal set, determine that the base station may not be accessedthrough the second terminal.

In at least one embodiment, the processor 520 is specifically configuredto: determine an access probability of the present service of the firstterminal or a terminal category of the first terminal; generate a randomnumber and calculate a probability of the random number; when theprobability of the random number meets the access probability, determinethat the base station may be accessed through the second terminal; andwhen the probability of the random number does not meet the accessprobability, determine that the base station may not be accessed throughthe second terminal.

In at least one embodiment, the state of the second terminal includeselectricity amount and load of the second terminal, and the processor520 is specifically configured to: determine the electricity amount orload of the second terminal according to the indication information;when the electricity amount is larger than a preset electricity amountthreshold value or the load of the second terminal is larger than apreset load threshold value, determine that the base station may beaccessed through the second terminal; and when the electricity amount issmaller than the electricity amount threshold value or the load of thesecond terminal is smaller than the load threshold value, determine thatthe base station may not be accessed through the second terminal.

In at least one embodiment, the indication information is included inDCI of a PHY layer of the discovery layer.

In at least one embodiment, the indication information is included in aMAC CE of the discovery signal.

In at least one embodiment, the indication information is included in aProSe protocol layer of the discovery signal.

Term “and/or” in the disclosure represent that there may exist threerelationships. For example, A and/or B may represent three conditions,that is, only A exists, both A and B exist and only B exists. Inaddition, character “/” in the disclosure usually represents that frontand rear associated objects form an “or” relationship.

Those of ordinary skilled in the art may realize that the units andalgorithm actions of each example described in combination with theembodiments disclosed in the disclosure may be implemented by electronichardware or a combination of computer software and the electronichardware. Whether these functions are executed in a hardware or softwaremanner depends on specific applications and design constraints of thetechnical solutions. Professionals may realize the described functionsfor each specific application by virtue of different methods, but suchrealization shall fall within the scope of the disclosure.

Those skilled in the art may clearly learn about that specific workingprocesses of the system, device and unit described above may refer tothe corresponding processes in the method embodiment and will not beelaborated herein for convenient and brief description.

In some embodiments provided by the application, it should be understoodthat the disclosed system, device and method may be implemented inanother manner. For example, the device embodiment described above isonly schematic, and for example, division of the units is only logicfunction division, and other division manners may be adopted duringpractical implementation. For example, multiple units or components maybe combined or integrated into another system, or some characteristicsmay be neglected executed. In addition, coupling or direct coupling orcommunication connection between each displayed or discussed componentmay be indirect coupling or communication connection, implementedthrough some interfaces, of the device or the units, and may beelectrical and mechanical or adopt other forms.

The units described as separate parts may or may not be physicallyseparated, and parts displayed as units may or may not be physicalunits, and namely may be located in the same place, or may also bedistributed to multiple network units. Part or all of the units may beselected to achieve the purpose of the solutions of the embodimentsaccording to a practical requirement.

In addition, each function unit in each embodiment of the disclosure maybe integrated into a processing unit, each unit may also existindependently, and two or more than two units may also be integratedinto a unit.

When being realized in form of software function unit and sold or usedas an independent product, the function may also be stored in acomputer-readable storage medium. Based on such an understanding, thetechnical solutions of the disclosure substantially or parts makingcontributions to the conventional art or part of the technical solutionsmay be embodied in form of software product, and the computer softwareproduct is stored in a storage medium, including a plurality ofinstructions configured to enable a piece of computer equipment (whichmay be a personal computer, a server, network equipment or the like) toexecute all or part of the actions of the method in each embodiment ofthe disclosure. The abovementioned storage medium includes: variousmedia capable of storing program codes such as a U disk, a mobile harddisk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magneticdisk or an optical disk.

The above is only the specific implementation mode of the disclosure andnot intended to limit the scope of protection of the disclosure. Anyvariations or replacements apparent to those skilled in the art withinthe technical scope disclosed by the disclosure shall fall within thescope of protection of the disclosure. Therefore, the scope ofprotection of the disclosure shall be subject to the scope of protectionof the claims.

1. A Device to Device (D2D)-based communication method, comprising:receiving, by a first terminal, a discovery signal of a second terminal,wherein the discovery signal comprises indication information and theindication information is configured to indicate a state of the secondterminal, the state of the second terminal comprises an electricityamount or load of the second terminal; determining, by the firstterminal, the electricity amount or load of the second terminalaccording to the indication information; determining, by the firstterminal, whether the base station can be accessed through the secondterminal according to the electricity amount or load of the secondterminal; and performing, by the first terminal, D2D communication withthe second terminal according to the state of the second terminal. 2.The method according to claim 1, wherein determining, by the firstterminal, whether the base station can be accessed through the secondterminal according to the electricity amount or load of the secondterminal comprises: when the electricity amount of the second terminalis larger than a preset electricity amount threshold value or the loadof the second terminal is larger than a preset load threshold value,determining, by the first terminal, that the base station can beaccessed through the second terminal; and when the electricity amount ofthe second terminal is smaller than the electricity amount thresholdvalue or the load of the second terminal is smaller than the loadthreshold value, determining, by the first terminal, that the basestation cannot be accessed through the second terminal.
 3. The methodaccording to claim 1, wherein performing, by the first terminal, D2Dcommunication with the second terminal according to the state of thesecond terminal comprises: when the first terminal determines that thebase station can be accessed through the second terminal, performing, bythe first terminal, D2D communication with the second terminal to accessthe base station.
 4. (canceled)
 5. The method according to claim 1,wherein the indication information is further configured to indicatewhether the second terminal allows another terminal to access the basestation through the second terminal.
 6. The method according to claim21, wherein the method further comprises: determining, by the firstterminal, whether a service type of a present service of the firstterminal belongs to the service type set, or whether the first terminalbelongs to the terminal set; when the service type of the presentservice belongs to the service type set or the first terminal belongs tothe terminal set, determining, by the first terminal, that the basestation can be accessed through the second terminal; and when theservice type of the present service does not belong to the service typeset or the first terminal does not belong to the terminal set,determining, by the first terminal, that the base station cannot beaccessed through the second terminal.
 7. The method according to claim1, wherein the method further comprises: generating, by the firstterminal, a random number, and calculating a probability of the randomnumber; when the probability of the random number meets the accessprobability, determining, by the first terminal, that the base stationcan be accessed through the second terminal; and when the probability ofthe random number does not meet the access probability, determining, bythe first terminal, that the base station cannot be accessed through thesecond terminal. 8.-9. (canceled)
 10. A terminal, which is a firstD2D-based communication terminal, the terminal comprising: atransceiver, configured to receive a discovery signal of a secondterminal, wherein the discovery signal comprises indication informationand the indication information is configured to indicate a state of thesecond terminal, the state of the second terminal comprises anelectricity amount or load of the second terminal; and a processor,configured to determine the electricity amount or load of the secondterminal according to the indication information, determine whether thebase station can be accessed through the second terminal according tothe electricity amount or load of the second terminal, and perform D2Dcommunication with the second terminal according to the state of thesecond terminal.
 11. The terminal according to claim 10, wherein theprocessor is specifically configured to: determine that the base stationcan be accessed through the second terminal when the electricity amountof the second terminal is larger than a preset electricity amountthreshold value or the load of the second terminal is larger than apreset load threshold value, and determine that the base station cannotbe accessed through the second terminal when the electricity amount ofthe second terminal is smaller than the electricity amount thresholdvalue or the load of the second terminal is smaller than the loadthreshold value.
 12. The terminal according to claim 10, wherein theprocessor is further configured to, when determining that the basestation can be accessed through the second terminal, perform D2Dcommunication with the second terminal to access the base station. 13.The terminal according to claim 10, wherein the indication informationis further configured to indicate whether the second terminal allowsanother terminal to access the base station through the second terminal.14. The terminal according to claim 10, wherein the indicationinformation is further configured to indicate that a service type set orterminal set for which the second terminal allows one or more terminalsother than the second terminal to access the base station through thesecond terminal.
 15. The terminal according to claim 10, wherein theprocessor is further configured to: generate a random number andcalculate a probability of the random number; when the probability ofthe random number meets the access probability, determine that the basestation can be accessed through the second terminal; and when theprobability of the random number does not meet the access probability,determine that the base station cannot be accessed through the secondterminal. 16.-17. (canceled)
 18. The terminal according to claim 10,wherein the indication information is comprised in Downlink ControlInformation (DCI) of a Physical (PHY) layer of the discovery layer. 19.The terminal according to claim 10, wherein the indication informationis comprised in a Media Access Control (MAC) Control Element (CE) of thediscovery signal.
 20. The terminal according to claim 10, wherein theindication information is comprised in a Proximity-based Service (ProSe)protocol layer of the discovery signal.
 21. The method according toclaim 1, wherein the indication information is further configured toindicate that a service type set or terminal set for which the secondterminal allows one or more terminals other than the second terminal toaccess the base station through the second terminal.
 22. The terminalaccording to claim 1, wherein the indication information is comprised inDownlink Control Information (DCI) of a Physical (PHY) layer of thediscovery layer.
 23. The terminal according to claim 1, wherein theindication information is comprised in a Media Access Control (MAC)Control Element (CE) of the discovery signal.
 24. The terminal accordingto claim 1, wherein the indication information is comprised in aProximity-based Service (ProSe) protocol layer of the discovery signal.25. The terminal according to claim 14, wherein the processor is furtherconfigured to determine whether a service type of a present service ofthe first terminal belongs to the service type set or whether the firstterminal belongs to the terminal set; when the service type of thepresent service belongs to the service type set or the first terminalbelongs to the terminal set, determine that the base station can beaccessed through the second terminal; and when the service type of thepresent service does not belong to the service type set or the firstterminal does not belong to the terminal set, determine that the basestation cannot be accessed through the second terminal.